Process of making biodiesel

ABSTRACT

The production of biodiesel is labor and time intensive. A first catalyst and a second catalyst were used for a two step transesterification of used oil to make biodiesel. The ratio of second catalyst and alcohol determines the outcome of good quality biodiesel that meets the ASTM standards. Several experiments were conducted to find optimal second catalyst, second catalyst alcohol ratio, and different times for adding second catalyst and alcohol either in sequence or simultaneously. Potassium hydroxide as a second catalyst and methanol as an alcohol, in a specific ratio calculated based glycerin value dictated the final volume. Specific ratio of catalyst and alcohol, when added together for a short duration lasting for minutes, instead of hours, produced superior quality biodiesel. The biodiesel production was stable and consistent. The production time was reduced considerably. Truncated method of producing biodiesel has tremendous cost and time advantage.

FIELD OF TECHNOLOGY

This disclosure relates generally to a process and a method of making biodiesel below American Society for Testing and Materials (ASTM) required standards. The invention further discloses the ratio optimization of potassium hydroxide (KOH) concentration and methanol, optimal time for adding the catalyst and alcohol and method of removing of water to make clean biodiesel.

BACKGROUND

Rapid growth in population coupled with industrial and technological developments are leading towards the depletion of fossil fuel resources in today's world. Biodiesel, an alternative diesel fuel, is a promising low cost, non-toxic and eco-friendly alternative. The process of making biodiesel is a method for developing an alternative renewable energy resource.

Many attempts are being made to utilize commercially used mixed oils to make biodiesel. However, many technical problems have to be overcome by possible treatments such as dilution with a suitable alcohol, emulsification, pyrolysis and transesterification.

Transesterification is a process of reacting a triglyceride such as mixed commercially used oil with an alcohol, usually methanol, in the presence of an alkaline catalyst to produce fatty acid esters (biodiesel) and glycerol. Alkaline-catalyzed transesterification process is normally adopted for biodiesel production because alkaline metal alkoxides and hydroxides are the most effective transesterification catalysts compared to the acid catalysts, although for economic reasons hydroxides are more often used. Transesterification occurs at a faster rate in the presence of an alkaline catalyst than in the presence of the same amount of acid catalyst. Sodium alkoxides (sodium methoxide, for example), Sodium methylate, KOH and NaOH are the most efficient catalysts used for this purpose. A number of manufacturers have identified the important variables that still affect the transesterification reaction, particularly, the reaction temperature, the type and amount of catalyst, the ratio of alcohol to mixed commercially used oil or vegetable oil, the mixing intensity and the reaction time, etc. These variables are a limiting factor is getting ASTM standard quality consistently and reproducibly at an industrial scale.

The typical process of transesterification reaction is shown below:

The time required for production of biodiesel is currently very long and the yield quality struggles to meet the ASTM standards. There is a need to optimize the biodiesel production process specifically the transesterification step to yield high quality biodiesel and reduce the biodiesel production time, so that the average producer is capable of producing high quality biodiesel for average consumers at a lower cost.

SUMMARY

The invention discloses a process and method for making a biodiesel and optimal catalyst concentration and time for achieving the same.

In one embodiment a two step transesterification method may be performed to obtain higher biodiesel yield. In another embodiment, both steps may have same and/or different catalysts.

In one embodiment, a process to calculate a formula was developed to calculate the amount of catalyst and the alcohol to be used. As a first step free fatty acid number was estimated by a conventional test used in the industry. In another embodiment, glycerin value was used to optimize the percentage ratio calculation of the catalyst to be used. The glycerin value multiplied by a percentage represents the gallons of catalyst to be used on an industrial scale. The catalyst amount multiplied by the glycerin value for used oil equals the gallons of alcohol to be used.

In one embodiment, a two step transesterification method to produce biodiesel is disclosed. The first step uses sodium methylate or sodium methoxide as a catalyst with methanol as an alcohol for the transesterification process. The subsequent step 2 may use KOH as a catalyst and methanol as an alcohol for producing biodiesel.

In another embodiment, the amount of KOH after the transesterification was determined and the ratio of methanol to KOH is disclosed. In another embodiment, the time of mixing the catalyst KOH to the used oil is disclosed.

In one embodiment, the mixing step of the KOH and the methanol to the used oil to make biodiesel is disclosed. The mixing of KOH and methanol to the used oil may be done sequentially or simultaneously. In one embodiment, the used oil was preheated to a certain degree so that transesterification may happen rapidly and the separation of glycerin and water is smoother.

In another embodiment, removing of water after the washing of biodiesel step is disclosed. This additional step ensures removal of any remaining water. The biodiesel is passed through the column of water adsorbent material. The water may adhere or get absorbed in the material and the cleaner biodiesel may be collected from the top of the column. The water may also settle at the bottom of the column due to gravity and may be removed.

In one embodiment, a method of producing a biodiesel having low ASTM values and performing ASTM tests after the experiment to determine the acceptable quality of the produced biodiesel is disclosed.

In one embodiment, a process of making biodiesel below required ASTM value is disclosed. In another embodiment, a two step process of making a cleaner biodiesel using two different catalysts is disclosed. In a further embodiment, a process of removing the water by passing the produced biodiesel through a water absorbent or adherent material for three times in sequence is disclosed.

The methods and processes disclosed herein may be implemented in any means for achieving various aspects, and may be used to produce biodiesel. Other features will be apparent from the accompanying drawings, tables and from the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:

FIG. 1 is a Prior art view of the Biodiesel formation by using a mixed methanol-catalyst combination in the conventional method.

FIG. 2 is a method of making and process of producing biodiesel by using a sequential step process of adding the catalyst and methanol for a fixed time sequentially for a shortened period.

FIG. 3 is a method of making and process of producing biodiesel by using a simultaneous step process of adding the catalyst and methanol for a fixed time sequentially for a shortened period.

Other features of the present embodiments will be apparent from the accompanying tables and from the detailed description that follows.

DETAILED DESCRIPTION

Several methods and processes for production of biodiesel (alternative renewable energy resource) are disclosed. Although the present embodiments have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments.

The instant application discloses that the claimed invention materially enhances the quality of the environment by contributing to development of renewable energy resources from used oil, such as restaurant oil, recycled oil etc. This application discloses an alternate energy source for conserving existing energy and making low cost biodiesel from used oil in a shortened period of time. The resultant biodiesel also meets and exceeds the ASTM standard required by the biodiesel industry. The instant application uses a two step biodiesel production process and describes a method and process of making low cost biodiesel. The basic catalyzed production of biodiesel generally occurs using the following steps as shown in FIG. 1 as prior art and the instant invention is shown in FIG. 2 and FIG. 3 and discussed in the following description.

As shown in FIG. 1, step 1, the vegetable oil, used cooking oil and/or animal fat is used as a starting material and will be represented as “used oil 102” throughout the application. The used oil may be but not limited to restaurant used oil, recycled oil and deep fried oil. The used oil 102 is allowed to sit for several hours in order to separate the solid particle contaminants by sedimentation process 106. The oil may be filtered to remove particles. The particles may be food particles, soap suds and/or any other solid particles. Once the contaminants are removed the oil is transferred to another container and heated 108 between 127-138° F.

Free fatty acid values are estimated using conventional laboratory tests, for example Saftest, to determine the amount of catalyst and alcohol to be added to transesterification reaction for step 1. Simultaneous mixing 109 of alcohol 104 and catalyst 108 may be done for several hours. The catalysts that may be typically used are sodium hydroxide (caustic soda) or potassium hydroxide (potash) or sodium methylate. The oil is mixed with the alcohol using a standard agitator or mixer. The predetermined weight of catalyst and premeasured amount of methanol may be added for a fixed amount of time. In this first step the catalyst may be sodium hydroxide (NaOH) or sodium methylate. The mixture may be continuously agitated using mixer 110 and the transesterification reaction may be conducted for 5-8 hours. The resultant glycerin 112 and biodiesel 121 are separated. The non transformed used oil 127 may be used in step 2.

As a next step ASTM test 105 may be performed for the used oil 127 before step 2 in order to determine the glycerin value for calculating the amount of catalyst 108 and alcohol 104 that needs to be added for transesterification process. Oil may be heated 140 throughout this procedure. The catalyst may be the same catalyst as used in the step 1.

The predetermined weight of catalyst 108 and premeasured amount of methanol 104 may be added (109) rapidly for 5-8 hours or longer. The resultant biodiesel 121B is passed through a water spray 116 chamber and ASTM value estimation 111 for biodiesel 121B is done prior to using it as a fuel 125 for a vehicle 130. This procedure is long and water content is not fully removed.

The novelty of the instant invention is using two different catalysts at different steps. As shown in FIGS. 2 and 3, in step 1 sodium methylate or sodium methoxide is used as a first catalyst for transesterification. As shown in FIG. 2 in step 2, in the instant invention the novel step (202) may be used to add the second catalyst KOH 108A into a closed reaction vessel containing the used oil 127 for only 5 minutes (210). After 5 minutes the methanol 104 may be added (203) to used oil 127B within 4 minutes (212). The system from here on may be totally closed to the atmosphere to prevent the loss of alcohol. The reaction mix may be kept just below the boiling point of the alcohol (around 146° F.) to speed up the reaction 150. Recommended reaction time varies from 4-5 minutes and the temperature may be between 135° F.-138° F. This invention is sequential addition of catalyst and alcohol. Excess alcohol may be normally used to ensure total conversion of the fat or oil to its esters.

In FIG. 3, another embodiment is disclosed. In step 2, simultaneous addition of catalyst 108 A (KOH) (302) and alcohol methanol 104 (203) is added simultaneously for 15 minutes for reaction 310. The transesterification reaction 150 produces biodiesel 121B and glycerin 112. The instant inventive step shows simultaneous addition of catalyst and alcohol.

In conventional procedure biodiesel may be washed after the glycerin is removed to wash any particulates or material that might remain in the biodiesel. As shown in FIGS. 1, 2 and 3 the resultant biodiesel 121B is passed through a water spray 116, which may be sprinkled using a water tube 114 through the column of biodiesel 121B. This step ensures that remaining catalyst, and other contaminants are removed from biodiesel 121B. The water 118 settles at the bottom of the chamber by gravity and is removed. However, still some water remains (FIG. 1) and in the instant invention a novel method for removing the remaining water is implemented (FIGS. 2 and 3). In the current invention an extra step is added to perform a unique removal of this water. Water once it remains in the biodiesel may create problems when used as fuel for machines. It is critical to remove the water after the washing step. Mechanical adhesion, electrostatic adhesion, chemical adhesion, dispersive adhesion and/or diffusive adhesion may also be used for achieving water separation. The biodiesel 121B is passed through a column of fiber glass wool or a water absorbent material 230 to remove the remaining water. The biodiesel may be passed from bottom to top through perforated tubes through the water adherent/absorbent material. The water adherent/absorbent material 230 is held in place by two plates on top and bottom. As the biodiesel 121B passes through the water adherent/absorbent material the water is absorbed or adhered to the material and the remaining biodiesel 121C is collected on the top via a tube. The process of passing the biodiesel 121B is repeated at least three times through three different columns and resultant biodiesel is collected for ASTM value estimation in step 209. The columns may contain the same or different water adherent/absorbent materials for efficient removal of the water. ASTM value analysis 111 was performed for the resultant biodiesel 121C. Accordingly, a test was also done using ASTM standards and flashpoint, cloud point, oxidation stability, acid number, cold soak test, total glycerin, triglycerides as triolein, diglyceride as diolein and monoglyceride as monoolein were estimated for certain examples as shown in Table 5 below. The resultant biodiesel 121C (FIGS. 2 and 3) is used as fuel 125 for vehicle 130.

Once the reaction is complete, two major products exist: glycerin 112 and biodiesel 121. Each has a substantial amount of the excess methanol that was used in the reaction. The reacted mixture may sometimes be neutralized at this step if needed. The glycerin phase is much denser than biodiesel phase and the two can be gravity separated with glycerin simply drawn off the bottom of the settling vessel. In some cases, a centrifuge may be used to separate the two materials faster.

The truncated transesterification time and calculation for amount of catalyst and alcohol is also one embodiment that differentiates the instant invention from the traditional method of making biodiesel. The resultant biodiesel has a very low ASTM number and the production time may be cut drastically to reduce cost and produce biodiesel efficiently.

Once the glycerin and biodiesel phases have been separated, the excess alcohol in each phase may be removed with a flash evaporation process or by distillation before the water spray wash. In others systems, the alcohol may be removed and the mixture neutralized before the glycerin and esters have been separated. In either case, the alcohol may be recovered using distillation equipment and may be re-used.

Several optimization processes and methods were done to arrive at optimum concentration of catalyst, alcohol, addition time, addition procedure, type of catalyst and the ratio of catalyst to the alcohol. The results of these methods and processes are shown in tables and discussed as follows.

TABLE 1 Sequential addition of catalyst sodium methylate and alcohol methanol USED OIL METER total METHANOL CATALYST TIME GLYCERIN (GALLONS) gallons (GALLONS) (GALLONS) (MINS) VALUE 4300 324 324 128 366 42 18 408 42 18 450 42 18 5.30 hours 0.84

900 gallons of Glycerin was removed from the above reaction. The resultant ASTM value was higher than the accepted value. The conclusion of the test was that sodium methylate and the methanol combination was at acceptable glycerin value to proceed to step 2. Potassium hydroxide was tested for the next set of experiments for step 2 transesterification processes.

TABLE 2 Process of mixing methanol in stages after a step of stopping. OIL KOH TIME METHANOL TIME STOP GLYCERIN EXPT 1 (Gallons) (Gallons) (mins) (Gallons) (mins) (mins) VALUE STEP 1 4000 96 5 0 4 4 STEP 2 5 180 2 10 0.11

Table 2 data shows the ASTM number to be well within the standards (acceptable value is 0.25). However, it is a two step process and is a bit unstable. This process may show that KOH and methanol are a good combination for the second half of the method of making biodiesel with acceptable ASTM values.

TABLE 3 Ratio optimization of KOH and Methanol KOH TIME METHANOL TIME ASTM (GALLONS) (MINS) (GALLONS) (MINS) VALUE 100 5 220 4 0.34 80 5 220 4 0.30 100 5 140 4 0.26 80 5 200 4 0.11 80 5 160 4 0.08

Table 3 shows that different combinations of KOH and methanol give different ASTM value. One part of KOH and two parts of methanol give the best results. This experiment also has spilt timings for adding the two components. The above experiments lead to calculation of optimal ratio of catalyst to alcohol.

Several percentages such as 30%, 25%, 20%, 15% and 10% as factor were tested and transesterification were performed in small lab scale volumes. However 20% as a factor resulted in the best ASTM value for the biodiesel. The following formula was finally used for industrial scale production of biodiesel with a starting material of 4000 gallons of used oil in step 2 for calculating catalyst and alcohol:

Glycerin value in gallons for the used oil×20% of the glycerin value in gallons=Catalyst (KOH) in gallons

Glycerin value in gallons=remove the decimal in front of glycerin value and convert it to gallons.

Catalyst (KOH) in gallons+glycerin value in gallons=Alcohol (methanol) in gallons

For example glycerin value=0.50. The minimum catalyst to be used would be 50 gallons. 50 gallons×20% of minimum gallons to be used=60 Gallons of Potassium Hydroxide 60 Gallons of Potassium Hydroxide+50 Gallons (glycerin value in gallons)=110 gallons of alcohol (methanol).

The factor may vary depending on the used oil quality and may range from 50-100% for calculations.

In order to achieve a single step experiment further studies were performed by adding the two components at the same time. Table 4 below shows some results.

TABLE 4 Single step addition of KOH and Methanol to achieve optimal results OIL KOH METHANOL TIME ASTM (GALLONS) (GALLONS) (GALLONS) (MINS) VALUE EXPT 1 4200 80 220 5 0.10 EXPT 2 4200 80 220 15 0.07

Table 4 data shows that the KOH and methanol can be added simultaneously and the time can be further reduced to get good ASTM value for resultant biodiesel.

ASTM analysis was performed for a batch of used oil 4600 gallons. The following experiment was performed and the starting used oil was 4600 gallons. In the first transesterification step 565 gallons of methanol and 186 gallons of sodium methylate. The glycerin value was 0.78. The second step of transesterification was performed using 80 gallons of potassium hydroxide and 220 gallons of methanol for 15 minutes. The resultant biodiesel was washed with water. The water was removed by passing it through a chamber containing fiber glass wool. The biodiesel was passed through three such chambers and finally clean biodiesel was collected and ASTM values and glycerin value was determined. The resultant glycerin value was 0.07. The resultant clean biodiesel may be used as fuel for automotives. Two step transesterification was performed as shown in FIG. 3 and the ASTM results are shown below in Table 5.

TABLE 5 ASTM numbers for an Experiment: LEVEL FOUND DETECTION ANALYSIS (UNITS) LIMITS METHOD Flashpoint >150° C. 4 ASTM D93 Could point 2.0° C. ASTM D2500 Oxidation Stability 10.0 hours 0.1 EN14112 Acid Number 0.18 mg KOH/g 0.05 ASTM D664 Cold Soak Test 103 sec 20 ASTM D 7501-09 Total Glycerin 0.138% mass 0.001 ASTM D6584 Free Glycerin n.d % mass 0.001 ASTM D6584 Triglycerides as 0.008% 0.001 ASTM D6584 Triolein Diglyceride as 0.023% 0.001 ASTM D6584 Diolein Monoglyceride as 0.106% 0.001 ASTM D6584 Monoolein

The resultant product produced by the method and the process used as shown in FIGS. 2 and 3 show very good ASTM values and is well below required standards.

In addition, it will be appreciated that the various examples and methods disclosed herein may be embodied using many different equipments and steps. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. 

1. A method for making an alternative renewable energy resource, comprising: adding a first catalyst and an alcohol as a first step transesterification process to an used oil to make biodiesel; determining a glycerin value number of the used oil to determine an amount for adding a second catalyst and an alcohol to optimize biodiesel production; heating the used oil to raise the used oil temperature; and adding the second catalyst and the alcohol using an adding process into the used oil for a predetermined time; wherein the adding process is at least one of a sequential process and a simultaneous process for adding the second catalyst and the alcohol.
 2. The method of claim 1, wherein the amount of the used oil to the second catalyst is equivalent to a total of a glycerin value number in gallons multiplied to 20% of the glycerin value number in gallons, wherein the amount of alcohol in gallons is equivalent to a second catalyst in gallons added to the glycerin value number in gallons.
 3. The method of claim 1, further comprising: mixing the content of the used oil, the second catalyst and the alcohol vigorously to produce a biodiesel and a glycerin; removing the glycerin and the alcohol; washing the biodiesel with a water spray in a chamber; removing the water using at least one of a water adherent and a water absorbent; estimating an ASTM number for the end product the biodiesel; and using the biodiesel as a fuel for a vehicle.
 4. The method of claim 1, wherein the first catalyst is at least one of sodium methylate, sodium hydroxide and sodium methoxide, the second catalyst is potassium hydroxide and the alcohol is methanol.
 5. The method of claim 1, wherein the predetermined time for adding the second catalyst is in the range of 4-7 minutes and the adding of alcohol is in the range of 3-6 minutes in the adding process in sequence.
 6. The method of claim 1, wherein the predetermined time for adding the second catalyst KOH and the alcohol methanol in the adding process simultaneously is 15 minutes.
 7. The method of claim 1, further comprising: settling the oil for a predetermined time prior to using for biodiesel production; removing sediment and water from the used oil prior to heating to a predetermined temperature; reacting with sodium methylate prior to mixing with the second catalyst and the alcohol; and removing the glycerin and estimating the glycerin value number by titrating to estimate the ratio of second catalyst and the alcohol.
 8. The method of claim 1, wherein the ASTM number is in the range of 0.07-0.25.
 9. The method of claim 8, wherein the ASTM number is 0.08.
 10. A process of making biodiesel, comprising: sedimenting a waste material and separating water from an used oil by at least one of centrifugation and holding for a predetermined time duration; reacting the used oil with sodium hydroxide to produce a glycerin and a saponified used oil; removing the glycerin from the saponified used oil and separating the water; estimating a glycerin value to calculate a catalyst and an alcohol content for a transesterification process; heating the oil to a temperature between 128° F.-140° F.; adding a second catalyst and an alcohol in sequence for a predetermined time; separating the water, the glycerin and the alcohol from a biodiesel; and estimating ASTM number for the biodiesel and storing the biodiesel.
 11. The process of claim 10, wherein the temperature is 138° F.
 12. The process of claim 10, wherein the predetermined time duration for adding second catalyst is 5 minutes, wherein the second catalyst is potassium hydroxide.
 13. The process of claim 10, wherein the predetermined time for adding the alcohol is 4 minutes and the alcohol is methanol.
 14. The process of claim 10, wherein the potassium hydroxide is added first and methanol is added later to the used oil.
 15. The process of claim 10, further comprising: mixing a factor determined by the glycerin value multiplied by 20% of glycerin value as the content of the second catalyst; and adding the second catalyst and the alcohol to the used oil mix to get a biodiesel of low ASTM value.
 16. The process of claim 15, wherein the second catalyst is potassium hydroxide and the alcohol is methanol.
 17. The process of claim 15, wherein the ASTM value is between the range of 0.07-0.25.
 18. A method of making a biodiesel, comprising: calculating a glycerin value for an used oil pretreated with a sodium hydroxide and a methanol; adding a calculated amount of potassium hydroxide as a result of glycerin value multiplied by a factor ranging from 5-80%; adding the potassium hydroxide and the methanol and stirring for 15 minutes; and harvesting the biodiesel and determining the ASTM factor for consumption.
 19. The method of claim 18, wherein the glycerin value is 0.65, the potassium hydroxide amount is 80 gallons and the methanol is 220 gallons for the used oil amount of 4600 gallons.
 20. The method of claim 18, further comprising: removing the methanol from the biodiesel prior to washing; washing the biodiesel through a water spray; and removing the water by passing through three different chambers to remove water to make biodiesel. 